GE L90 Instruction Manual page 609

CHAPTER 5: SETTINGS
Generally, this scheme uses an overreaching zone 2 distance element to essentially compare the direction to a fault at all
terminals of the line. Ground directional overcurrent functions available in the L90 can be used in conjunction with the
zone 2 distance element to key the scheme and initiate operation. This increases the coverage for high-resistance faults.
The scheme is intended for three-terminal and two-terminal applications with weak-infeed conditions. As a long reach of
the overreaching distance element can be required for three-terminal applications, transient blocking logic is provided for
both distance and ground directional overcurrent elements. In order to cope with weak-infeed conditions, an echo feature
is made available.
By default the scheme uses the reverse-looking zone 4 distance element to identify reverse faults. Additionally, reverse-
looking ground directional overcurrent functions can be used in conjunction with the zone 4.
For proper operation, the zone 2 and 4 phase and ground distance elements must be enabled, configured, and set per
rules of distance relaying. Enable the line pickup element, configure it, and set properly to detect line-end-open/weak-
infeed and undervoltage conditions. If used by the scheme, the selected ground directional overcurrent function(s) must be
enabled, configured, and set accordingly.
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
HYB POTT WEAK

INFEED: Enabled
HYB POTT W/I COND:

Off
HYB POTT RX PICKUP

DELAY: 0.000 s
TRANS BLOCK PICKUP

DELAY: 0.020 s
TRANS BLOCK RESET

DELAY: 0.090 s
ECHO DURATION:

0.100 s
ECHO LOCKOUT:

0.250 s
HYB POTT SEAL-IN

DELAY: 0.010 s
GND DIR O/C FWD:

Off
GND DIR O/C REV:

Off
HYB POTT NO OF COMM

BITS: 1
HYB POTT RX1:

Off
HYB POTT RX2:

Off
HYB POTT RX3:

Off
HYB POTT RX4:

Off
HYB POTT SCHEME

TARGET: Self-Reset
HYB POTT EVENT:

Disabled
Range: Disabled, Enabled, Custom
Range: FlexLogic operand
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: FlexLogic operand
Range: FlexLogic operand
Range: 1, 2, or 4
Range: FlexLogic operand
Range: FlexLogic operand
Range: FlexLogic operand
Range: FlexLogic operand
Range: Self-Reset, Latched, Disabled
Range: Disabled, Enabled
CONTROL ELEMENTS
5
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